Great Tool or Gold Standard? B-Type Natriuretic Peptide and Congestive Heart Failure

[West J Emerg Med. 2011;12(1):107-108.

A Chandra Study: Are Dwarf Carbon Stars Spun Up and Rejuvenated by Mass Transfer?

Carbon stars (with C/O> 1) were long assumed to all be giants, because only AGB stars dredge up significant carbon into their atmospheres. The case is nearly iron-clad now that the formerly mysterious dwarf carbon (dC) stars are actually far more common than C giants, and have accreted carbon-rich material from a former AGB companion, yielding a white dwarf and a dC star that has gained both significant mass and angular momentum. Some such dC systems have undergone a planetary nebula phase, and some may evolve to become CH, CEMP, or Ba giants. Recent studies indicate that most dCs are likely from older, metal-poor kinematic populations. Given the well-known anti-correlation of age and activity, dCs would not be expected to show significant X-ray emission related to coronal activity. However, accretion spin-up might be expected to rejuvenate magnetic dynamos in these post mass-transfer binary systems. We describe our Chandra pilot study of six dCs selected from the SDSS for Halpha emission and/or a hot white dwarf companion, to test whether their X-ray emission strength and spectral properties are consistent with a rejuvenated dynamo. We detect all 6 dCs in the sample, which have X-ray luminosities ranging from logLx= 28.5 - 29.7, preliminary evidence that dCs may be active at a level consistent with stars that have short rotation periods of several days or less. More definitive results require a sample of typical dCs with deeper X-ray observations to better constrain their plasma temperatures.Comment: 13 pages, 5 figures. Revised and resubmitted June 20, accepted June 21, 2019 to Ap

The life cycle of stars and their planets from the high energy perspective

One of the key research themes identified by the Astro2020 decadal survey is Worlds and Suns in Context. The Advanced X-ray Imaging Satellite (AXIS) is a proposed NASA APEX mission that will become the prime high-energy instrument for studying star-planet connections from birth to death. This work explores the major advances in this broad domain of research that will be enabled by the AXIS mission, through X-ray observations of stars in clusters spanning a broad range of ages, flaring M-dwarf stars known to host exoplanets, and young stars exhibiting accretion interactions with their protoplanetary disks. In addition, we explore the ability of AXIS to use planetary nebulae, white dwarfs, and the Solar System to constrain important physical processes from the microscopic (e.g., charge exchange) to the macroscopic (e.g., stellar wind interactions with the surrounding interstellar medium).Comment: This White Paper is part of a series commissioned for the AXIS Probe Concept Missio

Great Tool or Gold Standard? B-Type Natriuretic Peptide and Congestive Heart Failure

[West J Emerg Med. 2011;12(1):107-108.

Activity and Sedentary Time 10 Years After a Successful Lifestyle Intervention : The Diabetes Prevention Program

Introduction: This study aims to determine if evidence exists for a lasting effect of the Diabetes Prevention Program (DPP) lifestyle intervention on activity levels by comparing objectively collected activity data between the DPP Outcome Study (DPPOS) cohort and adults from the National Health and Nutrition Examination Survey (NHANES; 2003-2006). Methods: Average minutes/day of light and moderate to vigorous physical activity (MVPA) and sedentary behavior from ActiGraph accelerometers (collected 2010-2012) were examined (2013-2014) for comparable DPPOS and NHANES subgroups by age, sex, and diabetes status. Longitudinal questionnaire data on leisure activity, collected yearly from DPP baseline to the time of accelerometer measurement (1996-2010; 11.9-year mean follow-up), were also examined to provide support for a long-term intervention effect. Results: Average minutes/day of accelerometer-derived MVPA was higher in all DPPOS subgroups versus NHANES subgroups of similar age/sex/diabetes status; with values as much as twice as high in some DPPOS subgroups. Longitudinal questionnaire data from DPP/DPPOS showed a maintained increase of 1.24 MET hours/week (p=0.026) of leisure activity in DPPOS participants from all original study arms between DPP baseline and accelerometer recording. There were no consistent differences between comparable DPPOS and NHANES subgroups for accelerometer-derived sedentary or light-intensity activity minutes/day. Conclusions: More than 10 years after the start of DPP, DPPOS participants performed more accelerometer-measured MVPA than similar adults from NHANES. Longitudinal questionnaire data support the accelerometer-based findings by suggesting that leisure activity levels at the time of accelerometer recording remained higher than DPP baseline levels

Author Correction: The messy death of a multiple star system and the resulting planetary nebula as observed by JWST

International audienc

The messy death of a multiple star system and the resulting planetary nebula as observed by JWST

International audiencePlanetary nebulae—the ejected envelopes of red giant stars—provide us with a history of the last, mass-losing phases of 90% of stars initially more massive than the Sun. Here we analyse images of the planetary nebula NGC 3132 from the James Webb Space Telescope (JWST) Early Release Observations. A structured, extended hydrogen halo surrounding an ionized central bubble is imprinted with spiral structures, probably shaped by a low-mass companion orbiting the central star at about 40-60 au. The images also reveal a mid-infrared excess at the central star, interpreted as a dusty disk, which is indicative of an interaction with another closer companion. Including the previously known A-type visual companion, the progenitor of the NGC 3132 planetary nebula must have been at least a stellar quartet. The JWST images allow us to generate a model of the illumination, ionization and hydrodynamics of the molecular halo, demonstrating the power of JWST to investigate complex stellar outflows. Furthermore, new measurements of the A-type visual companion allow us to derive the value for the mass of the progenitor of a central star with excellent precision: 2.86 ± 0.06 M⊙. These results serve as pathfinders for future JWST observations of planetary nebulae, providing unique insight into fundamental astrophysical processes including colliding winds and binary star interactions, with implications for supernovae and gravitational-wave systems